The present invention relates to cooling structure of integrated circuit elements which constitute electronic units of information processing apparatus etc., and specifically relates to cooling structure of the type in which cooling fluid such as water is circulated around integrated circuit elements such that heat generated in the integrated circuit elements is transferred to the cooling fluid to thereby cool the integrated circuit elements.
Conventionally, such type of the cooling structure has a structure shown, for example, in FIG. 1 and disclosed in IBM J. RES DEVELOP Vol 26 No. 1 Jan. 1982 "A Conduction-Cooled Module for High-Performance LSI Devices" authored by S. Oktay and H. C. Kammerer. As shown in FIG. 1, an integrated circuit 101 (mounted on a lead pattern board 102 having I/0 pins 103) is placed in contact with a piston 104 biased against the integrated circuit 101 by means of a spring 105 to absorb heat from the integrated circuit 101, and the heat is transferred through a space 110 filled with helium gas to a hat 106 and an intermediate layer 107 and to a cooling plate 108 in which the heat is dissipated into cooling fluid 109.
However, in the conventional cooling structure of integrated circuit shown in FIG. 1, the piston is made contact with the integrated circuit by means of the spring to continuously apply force thereto, causing bad influence for the reliability of connection between the integrated circuit and the circuit board. In addition, in order to allow the piston to follow variation of hight and inclination produced when the integrated circuit is mounted on the circuit board, a contact portion of the piston to the integrated circuit is shaped spherical and a gap is provided between the hat and the piston. However, such structure reduces the effective heat-transfer area to thereby decrease the cooling efficiency. Moreover, since a cooling fluid passing in the cooling plate is formed for the purpose of heat transfer due to forced convection, the obtained heat-conduction coefficient is in the order of 0.1 to 0.5W/cm.degree. C. insufficient to cool the integrated circuit of high integration density having greater power consumption.
Further, Japanese laid-open patent application publication No. 160150/1985 discloses an cooling device of the type utilizing striking stream of cooling fluid. Namely, as shown in FIG. 2, heat generated by a chip 201 mounted on a printed circuit board 202 is transferred successively to a heat-conducting substrate 203, elastic heat-conducting material layer 204 and a heat-conducting plate 205. A nozzle 206 injects cooling fluid onto the heat-conducting plate 205 to cool the same. A tip of the nozzle 206 is sealed by the heat-conducting substrate 203, a cooling header 208 and bellows 207.
However, in the prior art structure of FIG. 2, since the bellows have a relatively small thickness, the bellows may be broken to form holes due to its corrosion to thereby leak out the cooling fluid.
There is another type of the conventional cooling structure of integrated circuits comprised of a cooling plate disposed in contact with top surfaces of integrated circuits, and a cooling container which constitutes pass of cooling fluid, in which these components are divided into two parts. This conventional cooling structure is, for example, disclosed in the Japanese patent application No. 183889/1985.
The above described conventional cooling structure of integrated circuits has a drawback that flow rate of cooling fluid must be regulated in proportion to heat amount generated by semiconductor chips of integrated circuits. Further, there is another drawback that the cooling plate in contact with the integrated circuits and the cooling container which forms pass of the cooling fluid are divided into two parts, thereby increasing thermal resistance to the integrated circuits.